Apparatus for forming optical aperture

ABSTRACT

An apparatus for forming an optical aperture comprises an object having a tip with a pointed end. Stoppers are disposed adjacent the tip. A pressing body applies a loading force to press the pointed end of the tip and at least a part of each of the stoppers to form an optical aperture at the pointed end of the tip. A load controller controls the loading force applied by the loader.

CROSS REFERENCE TO RELATED APPLICATIONS

The present application is a division of application Ser. No.09/997,819, filed on Nov. 30, 2001, now U.S. Pat. No. 6,684,676, whichis hereby incorporated by reference, and priority thereto for commonsubject matter is hereby claimed.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an apparatus for forming an opticalaperture. In particular, the present invention relates to an apparatusfor forming an optical aperture utilized in a near field device thatradiates and/or detects near field light.

2. Description of the Related Art

In order to observe microregions of the sample surface on the order ofnanometers, scanning probe microscopes (SPM) such as scanning tunnelingmicroscopes (STM) and atomic force microscopes (AFM) are used. SPM scansa sharpened probe on the sample surface, observes the interactionbetween the probe and the sample surface such as tunneling current oratomic force, and is able to obtain images with a resolution thatdepends on the probe tip shape. However, there are relatively severerestrictions on the sample.

Interest has been focused on scanning near field optical microscopes(SNOM) that observe the interaction between the near field generated onthe sample surface and the probe, thud enabling the observation ofmicroregions of the sample surface.

In SNOM, near field is irradiated to the sample surface from theaperture formed at the sharpened tip of an optical fiber. The aperturehas a size smaller than the diffraction limit of the light introducedinto the optical fiber, for example, about 100 nm in diameter. Theseparation between the aperture formed at the probe tip and the sampleis controlled by SPM technology, and is smaller than the aperture size.The spot size of the near field on the sample is approximately theaperture size. Therefore, by scanning the near field that is irradiatedon the sample surface, it is possible to observe the optical propertiesof microregions of the sample.

Not only for microscopes, but also for high density optical datarecording is it applicable by introducing light of relatively highintensity through the optical fiber probe towards the sample. Near fieldwith high energy density is generated at the optical fiber probeaperture, and it modifies either the structures or the propertieslocally of the sample surface. In order to obtain near field of highintensity, efforts have been made to increase the vertical angle.

In these devices utilizing near field, aperture forming is the mostimportant. As one apparatus for forming an aperture, an apparatusdisclosed in Japanese Patent Publication No.21201/1993 is known. In themanner of forming the aperture with this apparatus, a pointed lightwaveguide on which an opaque film is deposited is used as the object forforming the aperture. The method of forming the aperture is that thepointed light waveguide with an opaque film on the point is plasticallydeformed by pressing the pointed light waveguide against a hard flatplate with a very small amount of pressing, which is well-controlled bya piezoelectric actuator.

Another apparatus for forming an aperture is disclosed in JapanesePatent Laid-Open No.265520/1999. In the aperture forming apparatusdisclosed in Japanese Patent Laid-Open No.265520/1999, the object whichis to have an aperture is the point of a projection which is formed on aplate by FIB (Focused Ion Beam). The method of forming the aperture isthat FIB is irradiated on the side of the opaque film on the projectionpoint removing the opaque film on the point.

However, according to the method of Japanese Patent Publication No.21201/1993, the aperture can be formed on the light waveguide only oneby one. Additionally, a piezoelectric actuator having a movingresolution of a few nano meters is needed to control the amount ofpressing and thus an aperture forming apparatus has to be placed in anenvironment which is little influenced by vibration of other devices orair. Furthermore, it takes much time to adjust a waveguide rod tovertically abut on the flat plate. Moreover, in addition to thepiezoelectric actuator having a small moving amount, a mechanicaltranslation platform having a large moving amount is needed. Besides,when the pressing amount is controlled by using the piezoelectricactuator having a small moving resolution, a control unit is requiredand it takes a few minutes to control and form the aperture. Therefore,for aperture formation, a large-scale apparatus such as a high voltagepower supply or a feedback circuit is needed. In addition, a problem hasarisen that costs for aperture formation are increased.

Additionally, according to the method of Japanese Patent Laid-Open No.265520/1999, the fabrication object is the projection on the flat plate.However, since the aperture is formed by using the FIB, the timerequired to form one aperture is as long as ten minutes. Furthermore,because of using the FIB, a sample needs to be placed in vacuum. Thus, aproblem has arisen that fabrication costs for aperture fabrication areincreased.

SUMMARY OF THE INVENTION

The present invention overcomes the problems of the conventional art. Anapparatus for forming an optical aperture comprises an object having atip of conical or pyramidal shape, a stopper having almost the sameheight as that of the tip and an opaque film formed on the tip, andloading means for displacing a pressing body having approximately aplanar part covering the tip and at least a part of the stopper by aforce having a component acting toward the tip to form an aperture onthe point of the tip. According to the apparatus for forming an opticalaperture in the present invention, the displacement of the planar partof the pressing body is controlled by the stoppers which have almost thesame height as that of the tip. Therefore, by simply pushing the planarpart with a predetermined force it is easily possible to form an opticalaperture. Additionally, it is possible to form an aperture in variousenvironments such as in a vacuum, in a solution, and in the air.Furthermore, it does not require any specially designed controller whenit is forming an aperture, resulting in simplification of the apertureforming apparatus. Additionally, it is easy to shorten the duration timeof imposing the predetermined force, thus shortening the time foraperture formation and decreasing the cost of aperture formation.

A position controller sets a load target point to a load point of theloader. The load target point is disposed on a surface of the pressingbody and over top of the tip. It is possible to control the displacementof the pressing body by a predetermined load toward the load targetpoint. Therefore, optical apertures of uniform and minute size can beeasily formed, making it easy to improve the yield of formation ofoptical apertures.

The apparatus has a plurality of the loaders. The loaders are capable ofcontrolling the load for a plurality of load target points at the sametime. The load target points are on a surface of the pressing body andover top of the tips. Since the object for aperture formation comprisesplurality of tips and stoppers, it is possible to form an opticalaperture on each of the plurality of the tips simultaneously by imposingthe predetermined force on all the tips simultaneously. As a result, thefabrication time per an aperture can be shortened considerably, and thecost of aperture formation can be decreased.

A position controller for setting a load target point to a load point ofthe loader. The load target point being on a surface of the pressingbody and over top of the tip. An auto-controller controls the loader andthe position controller automatically. An automated control of theloading means and the positioning means results in the decrease in thecost of aperture formation.

Displacement of the pressing body, toward the tip for forming anaperture on a point of the tip, is generated by a weight strikingagainst the pressing body. The apparatus for aperture formation has asimple mechanism in which a weight falls freely, thus lowering the costof aperture formation.

The displacement of the pressing body, toward the tip for forming anaperture on a point of the tip, is generated by a pressure. Theapparatus for aperture formation has a simple mechanism with a pressuremeans, thus making it possible to form apertures with high precision ina stable manner. Besides, by controlling the pressure generated by thepressure means, the amount of the displacement of the pressing body canbe determined arbitrarily, thus making it possible to form apertures ofvarious sizes.

The displacement of the pressing body, toward the tip for forming anaperture on a point of the tip, is generated by a weight strikingagainst the pressing body, and the weight falls freely. A constantimpact can be imposed by a free-fall of a weight from a predeterminedheight. The amount of displacement can be kept constant, thus making itpossible to form optical apertures with high precision and low cost.

The displacement of the pressing body, toward the tip for forming anaperture on a point of the tip, is generated by a weight strikingagainst the pressing body. The weight falls freely along the arc from apredetermined angle with respect to a fulcrum axis. The impact caused bythe collision between the weight and the object for aperture formationcan be kept constant easily, thus making it possible and easy to formoptical apertures of uniform and minute size, and improving theproduction yields of aperture formation. Besides, the amount ofdisplacement of the pressing body can be determined arbitrarily bycontrolling the position of the fulcrum and the weight, thus making itpossible to form apertures of various sizes.

The loader works by a spring force of a pressure spring. By controllingthe pressure means with the spring force, it is possible to control theamount of displacement of the pressing body, thus making it possible andeasy to form minute optical apertures of uniform size, and improve theproduction yields of the optical aperture formation. Besides, since theamount of the displacement of the pressing body can be controlled by thespring force, it is easy to form apertures of various sizes.

The loader works by magnets being moved by magnetic repulsive orattractive force. By controlling the pressure means with the magneticforce, it is possible to control the amount of displacement of thepressing body, thus making it possible and easy to form minute opticalapertures of uniform size, and improve the production yields of theoptical aperture formation. Besides, since the amount of thedisplacement of the pressing body can be controlled by the spring force,it is easy to form apertures of various sizes.

A work has the object for aperture. A magnifying glass measures amountof the work's curve. A load controller controls a direction of theloader to make the direction being perpendicular to the tip. Even whenmultiple tips are formed on a substrate, a constant load is applied forindividual tip, thus making it possible to form optical apertures inmass production.

A work has the object for aperture, a magnifying glass measuring foramount of the work's curve. An auto-controller controls the position ofthe work to make a direction of the loader being perpendicular to thetip. A simple mechanism can control the load direction for individualtip, thus making it possible to form optical apertures with highprecision. Besides, an automation of the production process is easy,thus making mass production possible. Optical apertures can be suppliedwith low cost.

The apparatus has a plurality of the pressing bodies. Multiple aperturescan be formed at once, thus making it possible to form many aperturesquickly, and lowering the production cost of apertures.

A cleaner cleans a surface of the pressing body. When one presser formsapertures repeatedly, an accretion attached on the surface of thepresser hinders the aperture formation. In this invention, a cleaningmechanism cleans the surface of the presser, thus making it possible toform apertures continuously in a stable manner.

A presser presses the pressing body. The presser has a spherical shapefacing the pressing body. A limited area of the presser receives theforce, thus making it easy to deform the presser. Even when the stopperis higher than the tip, it is possible to form apertures.

A presser displaces the pressing body. A surface of the presser thatfaces the pressing body is made of a material. The material is softerthan the pressing body. Even when the surface of the pressing body isnot flat, a uniform force can be applied onto the pressing body, thusmaking it possible to form apertures of uniform size in a stable manner.A presser displaces the pressing body. The pressing body has a groove ofinverted pyramid shape. The presser has a shape that can gear with thegroove on the pressing body. The pressure area for the presser can beeasily defined, thus making it possible to form apertures with highdimension precision in a stable manner.

A work has the object for aperture formation. A stage for being loadedwith the work; wherein the work is fixed on the stage. There is noproblem of a variation in the aperture sizes when the substrate curves,which would be caused by a variation in the force onto the light guidingbody depending on the location on the substrate. Besides, the apparatushas a simple mechanism with vacuum equipment that can be installedeasily to the stage. The uninstallation of the substrate is also easy.

BRIEF DESCRIPTION OF THE DRAWINGS

The teachings of the invention can be readily understood by consideringthe following detailed description in conjunction with the accompanyingdrawings, in which:

FIG. 1 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 1 of the invention;

FIG. 2 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 1 of the invention;

FIG. 3 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 1 of the invention;

FIGS. 4A and 4B depict diagrams illustrating a method for fabricating awork 1000;

FIGS. 5A and 5B depict diagrams illustrating the method for fabricatingthe work 1000;

FIG. 6 depicts diagrams illustrating a relationship between the heightsof the tip 1 and the stopper 2 in the method for fabricating the work1000;

FIGS. 7A to 7C depict diagrams illustrating a relationship between theheights of the tip 1 and the stopper 2 in the method for fabricating thework 1000;

FIGS. 8A and 8B depict diagrams illustrating an apparatus for formingthe aperture in an embodiment 2 of the invention;

FIGS. 9A and 9B depict diagrams illustrating an apparatus for formingthe aperture in an embodiment 3 of the invention;

FIGS. 10A and 10B depict diagrams illustrating an apparatus for formingthe aperture in an embodiment 4 of the invention;

FIGS. 11A and 11B depict an image observed with the magnifying glassabove the work 1000, and an image obtained by converting the image intoa binary image in an embodiment 5 of the invention;

FIGS. 12A and 12B depict diagrams illustrating an apparatus for formingthe aperture in an embodiment 6 of the invention;

FIG. 13 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 6 of the invention;

FIG. 14 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 7 of the invention;

FIG. 15 depicts a diagram illustrating a method for removing theaccretion in an embodiment 7 of the invention;

FIG. 16 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 7 of the invention;

FIG. 17 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 7 of the invention;

FIGS. 18A and 18B depict diagrams illustrating an apparatus for formingthe aperture in an embodiment 8 of the invention;

FIG. 19 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 8 of the invention;

FIGS. 20A and 20B depict diagrams illustrating an apparatus for formingthe aperture in an embodiment 9 of the invention;

FIG. 21 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 10 of the invention;

FIG. 22 depicts a diagram illustrating an apparatus for forming theaperture in an embodiment 11 of the invention;

FIG. 23 depicts a diagram illustrating the state of the work 1002 whenit is not vacuum chucked;

FIG. 24 depicts a diagram illustrating the state of the work 1002 withthe plate 728 on the work 1002 when the work 1002 is not vacuum chucked;

FIG. 25 depicts a diagram illustrating the state of the work 1002 onwhich a load is imposed by the plate 728 and the presser 729 when thework 1002 is not vacuum chucked;

FIG. 26 depicts a diagram illustrating the state of the work 1002 onwhich a load is imposed by the plate 728 and the presser 729 when thework 1002 is not vacuum chucked;

FIG. 27 depicts a diagram illustrating the curved work 1003 which isvacuum chucked and placed on the stage;

FIG. 28 depicts a diagram illustrating the work 1003 which is vacuumchucked and on which the plate 733 is placed; and

FIG. 29 depicts a diagram illustrating the work 1003 which is vacuumchucked, and on which a load is imposed by the plate 733 and the presser734.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereafter, the apparatus for forming the aperture of the invention willbe described in detail with reference to the accompanying drawings.

[Embodiment 1]

The apparatus for forming the aperture of the invention will bedescribed referring to FIGS. 1 to 3. FIG. 1 is a cross-sectional diagramshowing a schematic configuration of the work 1000. As shown in thedrawing, the work 1000 comprises a transparent layer 5 formed on asubstrate 4, a tip of conical or pyramidal shape 1 and a ridge-shapedstopping member (hereinafter “stopper”) 2 formed on the transparentlayer 5, and an opaque film 3 formed on the tip 1, the stopper 2 and thetransparent layer 5. Additionally, the transparent layer 5 is notnecessarily needed here; in that case the opaque film 3 would be formedon the tip 1, the stopper 2 and the substrate 4. Furthermore, the opaquefilm 3 may be deposited only on the tip 1.

A height H1 of the tip 1 is equal to or under a few millimeters; aheight H2 of the stopper 2 is equal to or under a few millimeters. Thedistance between the tip 1 and the stopper 2 is equal to or under a fewmillimeters. Besides, a thickness of the opaque film 3 is from a fewtens to a few hundreds of nanometers, depending on the materials of theopaque film 3.

For the tip 1, the stopper 2 and the transparent layer 5, a dielectrichaving high transmissivity in the range of visible light such as SiO₂,SiN or diamond, a dielectric having high transmissivity in the range ofinfrared light such as SeZn or silicon, or a dielectric having hightransmissivity in the range of ultraviolet light such as MgF or CaF isused. Additionally, as a material for the tip 1, any material may bepreferable that is even a little transparent to an optical wavelengthregion of a light passing through the aperture. Furthermore, the tip 1,the stopper 2 and the transparent layer 5 may be configured of the samematerial or different materials. For example, the tip 1 may beconfigured of silicon oxide, and the stopper 2 may be monocrystalsilicon. Moreover, the stopper 2 may be configured of a plurality ofmaterials such as a double-layer structure of monocrystal silicon andsilicon oxide. Particularly, the stopper 2 does not need to betransparent to lights. The configuring materials may include a lightshielding material such as metals or alloys thereof. Besides, the tipmay be configured of various dielectrics, obviously. For the opaque film3, for example, metals such as aluminum, chromium, gold, platinum,silver, copper, titan, tungsten, nickel, cobalt, and alloys thereof areused. In addition, the substrate 4 may be a transparent material. Thetip 1, the stopper 2, the transparent layer 5 and the substrate 4 may bemade of the same material.

FIG. 2 depicts a diagram illustrating a state in which the opaque film 3on the tip 1 is being plastically deformed in the apparatus for formingthe aperture. A plate 6 is placed on the work 1000 shown in FIG. 1. Theplate 6 covers at least a part of the stopper 2 and the tip 1. The plate6 has a planar portion to come into contact with the tip 1 and thestopper 2. Further, a presser 7 is placed on the plate 6. A loadergenerates a force F. The force F is applied to the presser 7 in thecentral axis of the tip 1 and thereby the plate 6 moves toward the tip1. Compared with a contact area of the tip 1 to the plate 6, a contactarea of the stopper 2 to the plate 6 is a few hundreds to a few tenthousands times greater. Therefore, the applied force F is dispersed bythe stopper 2 and consequently the displacement of the plate 6 becomessmaller. Since the displacement of the plate 6 is small, the amount ofplastic deformation applied to the opaque film 3 is very small.Additionally, the tip 1 and the stopper 2 only receive a very smallplastic deformation. One way to apply the force F is such that a weighthaving a predetermined weight is raised to a predetermined distance forfree-fall, or a spring having a predetermined spring constant is mountedon the presser 7 to press the spring for a predetermined distance. As amaterial for the plate 6, a metal such as Al, Cr, Au and W, a dielectricsuch as SiO₂, SiN and diamond, a semiconductor material such as Si, Geand GaAs, ceramics materials or a material transparent in the range ofvisible light is used. Particularly, in the case that the plate 6 ismade of a material harder than the opaque film 3 and softer than the tip1 and the stopper 2, a force that is applied to the tip 1 and thestopper 2 is absorbed by the plate 6, and thus the displacement of theplate 6 becomes smaller. Therefore, the amount of plastic deformation ofthe opaque film 3 is made smaller easily.

In addition, this embodiment, the structure for applying a load onto theobject for aperture forming that consists of a tip 1, a stopper 2, andan opaque film 3 is a plate 6 and a presser 7. However, there may becases where either a plate 6 or a presser 7 alone can be used to applyload onto the object for forming the aperture. In these cases astructure for applying a load onto the object for aperture forming maybe called a pressing device or pressing body.

In addition, the plate 6 may be a transparent plate. In this case, theposition of the apex of the tip 1 can be confirmed from above thetransparent plate.

FIG. 3 depicts a state in which the plate 6 and the presser 7 areremoved after the force F has been applied. The amount of plasticdeformation of the opaque film 3 is very small and the tip 1 and thestopper 2 are deformed only in a plastic deformation region. Therefore,an aperture 8 is formed at the point of the tip 1. The size of theaperture 8 is from about a few nanometers to the extent of thediffraction limit of the optical wavelength of the light passing throughthe tip 1. Additionally, in the description mentioned above, the plate 6is inserted between the presser 7 and the work 1000. However, it isneedless to say that the plate 6 can be omitted and the work 1000 isdirectly pressed by the presser 7 to similarly form the aperture 8. Inorder to enter a light to the aperture 8, the substrate 4 is etched fromthe side opposite to the side where the tip 1 is formed to expose atransparent layer 5 or at least a part of the tip 1 and thereby anentrance for light to the aperture 8 is formed. Furthermore, it goeswithout saying that the substrate 4 is configured of a transparentmaterial and thereby a process for forming the entrance for light can beomitted.

As described above, according to the apparatus for producing theaperture of the invention, the amount of displacement of the plate 6 canbe controlled excellently by the stopper 2 and can be made very small.Thus, the aperture 8 having a uniform and small size can be produced onthe point of the tip 1 easily. Additionally, the near field light can begenerated from the aperture 8 by irradiating a light from the substrateside.

FIGS. 8A and 8B depict the apparatus for forming optical aperture inembodiment 1.

FIG. 8A is the structure diagram of the aperture forming apparatus. FIG.8B shows the image of the work 1000 and the transparent plate 60observed from above by the magnifying glass 402.

As shown in FIG. 8A, the apparatus consists of a stage 401, a loadcontroller 300, and a magnifying glass 402. The stage 401 is placedhorizontally so that the work 1000 and the transparent plate 60 can beplaced parallel in contact with one another. The stage 401 includes adouble axis ball screw stage in order to move horizontally in a plane.

The load controller 300 is designed so that the weight 301 falls freelyfollowing the arc from a predetermined angle with respect to the fulcrumaxis 303 being the fulcrum. The rotation gear 302 consists of clutchesand a combination gears. When the rotation gear is rotated in apredetermined direction, the weight 301 is lifted to a predeterminedangle. When the rotation gear is further rotated, the weight 301 fallsfreely.

Furthermore, the stage 401 and the load controller 300 are arranged insuch positions that the load point 304 at the tip of the weight 301applies a load vertically onto a load target point 201 when the weight301 of the load controller 300 falls. The load target point 201 is on asurface of the transparent plate 60 and over top of the tip.

The magnifying glass 402 consists of a microscope with a cross scale onits optical axis, or a CCD camera. The magnifying glass 402 is locatedin a relative position to the fulcrum axis 303 so that the load point304 should be on the center of the cross scale.

After the work 1000 is placed on the stage 401, the stage 401 is movedby a position controller so that the load target point 201 should be onthe cross scale of the magnifying glass 402. Next, by rotating therotation gear 302 of the load controller 300, the weight 301 fallsfreely from a predetermined angle, applying a predetermined load ontothe load target point 201. Thus an optical aperture formed on the tip 1on the work 1000.

The force F onto the load target point 201 depends on the angle and theweight of the weight 301 of the load controller 300. The force F isdetermined by the aperture size, the material of the plate 6, and thethickness and the material of the opaque film 3. The tip of the weight301 has a spherical shape so that the load point area for the loadtarget point 201 becomes as small as possible.

As described above, according to the aperture forming apparatus in thisinvention, it is possible to apply a constant load onto the load targetpoint with high precision, thus making it possible to form opticalapertures in a stable manner. Furthermore, the cost of the wholeapparatus is low, making it possible to form optical apertures with lowcost.

Furthermore, there may be a plurality of loaders that are capable ofcontrolling the load for a plurality of load target pointssimultaneously. In such a case, since the object for aperture formingconsists of a plurality of tips and stoppers, it is possible to formoptical apertures on a plurality of tips at once by applying the forcein the block, thus shortening the fabrication time per aperture, andlowering the production cost of optical apertures.

Next, a method for fabricating the work 1000 will be described referringto FIGS. 4A, 4B, 5A and 5B. FIGS. 4A and 4B illustrate a state in whichthe transparent material 103 is formed on a substrate material 104 andthen a tip mask 101 and a stopper mask 102 are formed. FIG. 4A depicts atop view and FIG. 4B depicts a cross-sectional view at a position shownby A–A′ of FIG. 4A. The transparent material 103 is formed on thesubstrate material 104 by the chemical vapor deposition (CVD), thephysical vapor deposition (PVD) or the spin coating. Additionally, thetransparent material 103 can be formed on the substrate material 104 bythe solid state bonding or gluing as well. Then, the tip mask 101 andthe stopper mask 102 are formed on the transparent material 103 by thephotolithography process. The tip mask 101 and the stopper mask 102 maybe formed simultaneously or separately.

For the tip mask 11 and the stopper mask 102, a photo-resist or anitride film is generally used. These may be selected properly inaccordance with a material of the transparent material 103 and anetchant to be used in the subsequent process. For the transparentmaterial 103, a dielectric having high transmissivity in the range ofvisible light such as SiO₂ or diamond, a dielectric having hightransmissivity in the range of infrared light such as SeZn or Si, or adielectric having high transmissivity in the range of ultraviolet lightsuch as MgF or CaF is used.

A diameter of the tip mask 101 is a few millimeters, for example. Awidth W1 of the stopper mask 102 is equal to the diameter of the tipmask 101 or a few tens nanometers to a few micrometers smaller thanthat. Additionally, the width W1 of the stopper mask 102 may be from afew tens nanometers to a few micrometers greater than the diameter ofthe tip mask 101. Furthermore, a length of the stopper mask 102 is notless than a few tens micrometers.

FIGS. 5A and 5B illustrate a state in which the tip 1 and a plurality ofstoppers 2 have been formed. FIG. 5A is a top view and FIG. 5B is across-sectional view at a position shown by A–A′ in FIG. 5A. After thetip mask 101 and the stopper mask 102 are formed, the tip 1 and thestoppers 2 are formed by the isotopic etching in wet etching. Adjustingthe relationship among a thickness of the transparent material 103 andthe heights of the tip 1 and the stoppers 2 may form or not form thetransparent layer 5 shown in FIG. 1. A diameter of the point of the tip1 is from a few nanometers to a few hundreds nanometers. After that, theopaque film is deposited by sputtering or vacuum evaporation and therebythe work 1000 shown in FIG. 1 can be formed. Additionally, in the casethat the opaque film 3 is deposited only on the tip 1, a metal maskhaving a topology to deposit the opaque film on the tip 1 is placed toperform sputtering or vacuum evaporation in the deposition process ofthe opaque film 3. Furthermore, it is needless to say that after theopaque film 3 is deposited on the entire surface where the tip of thework 1000 has been formed, using the photolithography process in whichthe opaque film 3 remains only on the tip 1 can form the opaque film 3only on the tip 1.

FIGS. 6, 7A, 7B and 7C are diagrams illustrating the relationshipbetween the heights of the tip 1 and the stopper 2 in the method forfabricating the work 1000 as described above. In addition, hereafter,only the case in which the diameter of the tip mask 101 is smaller thanthe width of the stopper mask 102 will be described. FIG. 6 is a diagramillustrating only the tip 1 and the stopper 2 in the process describedin FIG. 5A. FIGS. 7A to 7C are cross-sectional views illustrating thetip 1 at a position shown by B–B′ in FIG. 6 and the stopper 2 at aposition shown by C–C′ in the FIG. 6.

FIG. 7A is a diagram illustrating a state in which the tip 1 has beenformed. The width of the stopper mask 102 is greater than the diameterof the tip mask 101. Thus, a flat portion is left on the top of thestopper 2 and the stopper mask 102 is left on this flat portion in thestate of FIG. 7A. However, the tip mask 101 has a very small contactarea to the tip 1 and therefore it comes off. In the state of FIG. 7A, aheight H11 of the tip 1 is the same as a height H22 of the stopper 2.

FIG. 7B illustrates a state in which further proceeding etching from thestate of FIG. 7A, the flat portion on the top of the stopper 2 is justremoved. When etching is performed from the state of FIG. 7A, a heightH111 of the tip 1 having no tip mask 101 is lowered gradually, whereas aheight H222 of the stopper 2 remains the same as the height H22. A widthof the flat portion of the top of the stopper 2 becomes narrowergradually and its cross-sectional shape becomes triangular as shown inFIG. 7B. A difference ΔH between the heights of the tip 1 and thestopper 2 at this time is about 1000 nm or under, varying according tothe difference between the diameter of the tip mask 101 and the width ofthe stopper mask 102 and a point angle between the tip 1 and the stopper2.

FIG. 7C illustrates a state in which etching further proceeds from thestate of FIG. 7B. A height H1111 of the tip 1 becomes lower than theH111. Similarly, a height H2222 of the stopper 2 also becomes lower thanthe height H222. However, a reduced amount of the height H1111 is equalto that of H2222 and thus the difference ΔH between the heights of thetip 1 and the stopper 2 does not change. Additionally, in the case thatthe width of the stopper mask 102 is smaller than the tip mask 101, therelationship between the heights of the tip 1 and the stopper 2 is onlyreverse. Furthermore, in the case that the tip mask 101 is equal to thestopper mask 102, it is needless to say that the height of the tip 1becomes equal to that of the stopper 2.

According to the method for fabricating the work 1000 of the invention,the difference ΔH between the heights of the tip 1 and the stopper 2 canbe controlled excellently by the photolithography process. Therefore, inthe method for producing the aperture described in FIGS. 1 to 3, thedisplacement of the plate 6 can be controlled excellently.

As described above, according to the embodiment 1 of the invention, theheights of the tip 1 and the stopper 2 can be controlled excellently anddisposing the stopper 2 can make the displacement of the plate 6smaller. Therefore, the aperture 8 having a uniform and minute size canbe formed on the point of the tip 1 easily without using an actuatorhaving high resolution. Our experiment shows that the aperture 8 havinga diameter of 100 nm or under could be formed by only tapping thepresser 7 with a hammer in hand. Additionally, the heights of the tip 1and the stopper 2 are controlled excellently and thus the productionyields of the aperture 8 were improved. Furthermore, the work 1000described in the embodiment 1 can be fabricated by the photolithographyprocess. Thus, multiple works can be fabricated on a sample having alarge area such as a wafer. The force F is held constant and thereby theapertures 8 having a uniform aperture diameter can be formed on therespective works 1000. Moreover, changing the force F is extremelysimple so that the apertures 8 having a different aperture diameter canbe formed separately on the multiple works 1000 that have beenfabricated. Besides, simply applying the force F forms the aperture 8and thus the time to produce the aperture is as short as from a fewseconds to a few tens seconds. In addition, according to the embodiment1 of the invention, any fabrication environment is acceptable.

Therefore, fabrication in the atmosphere is possible and fabricationstates can be observed by an optical microscope instantly. Additionally,fabrication in a scanning electron microscope makes it possible toobserve fabrication states with higher resolution than the opticalmicroscope. Furthermore, by fabrication in a liquid, the liquid servesas a damper and thus fabrication conditions of improved controllabilitycan be obtained.

Moreover, the force F is applied to the sample fabricated with aplurality of the works 1000 in the block and thereby the apertures 8having a uniform aperture diameter can be produced at one time as well.In the case of fabrication in the block, the fabrication time peraperture becomes as short as a few hundreds milliseconds or under,depending on the number of the works 1000 per wafer.

[Embodiment 2]

The apparatus for forming optical aperture in embodiment 2 of theinvention is described referring to FIGS. 8A and 8B.

FIG. 8A depicts the diagram of the aperture forming apparatus. FIG. 8Bshows an obtained image of the work 1000 and the transparent plate 60observed from above by the magnifying glass 402.

A detailed description of the portion that is identical to embodiment 1is omitted.

The rotation gear 302 of the load controller 300 comprises a rotationmotor, clutches, and combination gears. The rotation motor is able tocontrol the rotation angle, and it can be, for example, a combination ofa stepping motor, DC motor, and an angle sensor. The magnifying glass402 uses a CCD camera. The stage 401 is an XY stage with an interfacesuch as GPIB. The load controller is controlled by the auto-controller403.

The auto-controller 403 can be a personal computer. It receives imagedata from the magnifying glass 402, adjusts the load target point 201 tothe load point 304, and then rotates the motor of the rotation gear 302so that the weight 301 falls freely. The auto-controller 403 isprogrammed so that the above described operations can be donesequentially.

As described above, according to the apparatus for forming opticalaperture in the present invention, it is possible to impose a constantload onto the load target point repeatedly with high precision. It ismade possible by this invention to form optical aperture in a stablemanner. Furthermore, the cost of the apparatus is low leading to lowcost production of optical apertures.

It is also possible to form sequentially an optical aperture on aplurality of the object for aperture formation on the work 1000. Massproduction of optical apertures is possible with low cost.

[Embodiment 3]

FIGS. 9A and 9B depict the apparatus for forming optical aperture inembodiment 3. FIG. 9A shows the details of the load controller of theapparatus. FIG. 9B shows that load is being imposed on the plate 6 bythe load controller.

Description of the parts that are common to embodiment 1 or 2 isomitted.

The rotation gear 502 of the load controller 500 consists of therotation motor 501, clutches, and combination gears. The rotation gear501 is able to control the rotation angle. The rotation gear 501 can bea combination of, for example, a stepping motor, a DC motor, and anangle sensor. When the rotation gear 502 is rotated in the directionindicated as an arrow in FIGS. 9 a and 9B, the pressure spring 503 ispushed. A constant pressure is imposed on the load target point 201 byboth the shape of the rotation gear 502 and the rotation speed of therotation motor 501. The load on the load target point 201 depends on theshape of the rotation gear 502 and the spring force of the pressurespring 503. This load is determined by the material of the plate 6, thethickness of the opaque film 3, and the material of the opaque film 3.The tip of the pressure spring 503 has a spherical shape so that theload point area for the load target point becomes as small as possible.

By controlling the rotation speed of the rotation motor 501, it is easyto control the load on the load target point, thus it is easy to obtainan aperture of arbitrary size.

[Embodiment 4]

FIGS. 10A and 10B depict the apparatus for forming optical aperture inembodiment 4. FIG. 10A shows the details of the load controller of theapparatus. FIG. 10B shows that load is being imposed on the plate 6 bythe load controller.

Description of the parts that are common to embodiment 1, 2, or 3 isomitted.

The load controller 600 comprises a coil 602 and a magnetized iron core601. The electric current direction in the coil 602 moves the iron core601 vertically. The plate 6 that acts as a pressing body has the loadtarget point 201. A constant load can be imposed on the load targetpoint 201 resulting in formation of optical aperture on the tip 1 on thework 1000. The load on the load target point depends on the electriccurrent inside the coil 602. This load is determined by the aperturesize, the material of the plate 6, the material of the opaque film 3,and the thickness of the opaque film 3. The tip of the iron core 601 hasa spherical shape so that the load point area for the load target point201 becomes as small as possible. By controlling the electric currentand the duration time, it is possible to control the load on the loadtarget point, and thus easy to obtain an aperture of arbitrary size.

Furthermore, since it can be controlled electrically, a personalcomputer can be used to control, thus automation is easy, and massproduction is possible. Aperture formation is made inexpensive.

[Embodiment 5]

In embodiment 5, the same structure as in FIG. 8A in embodiment 2 isused. FIG. 11A shows the image of the work 1000 and the transparentplate 60 observed from above by the magnifying glass 402. FIG. 11B showsthe image which is obtained by converting the image in FIG. 11A intobinary format. The conversion is made by the auto-controller 403. InFIG. 8A The horizontally placed stage 401 has a structure such that thework 1000 and the transparent plate 60 can be placed in parallel. Thework 1000 and the transparent plate 60 are in contact. The stage 401comprises a double axis (xy) stage (not shown), and a double axisgoniostage (not shown). The xy stage locates the load point of the loadcontroller 300 onto the load target point 201 for each of the tips onthe work 1000. The goniostage adjusts the inclination of the work thatis caused by the curve or the variation in the film thickness.

For the xy stage, a conventional stage of planar motion type such asball screw type is used. For the goniostage, a conventional stage iscombined with the xy stage.

The load controller 300 is designed such that the weight 301 fallsfreely along the arc from a predetermined angle with respect to thefulcrum axis 303. The rotation gear 302 consists of clutches and acombination gears. When the rotation gear 302 is rotated in a particulardirection, the weight 301 is lifted to a predetermined angle. When therotation gear 302 is further rotated, the weight 301 falls freely. Thestage 401 and the load controller 300 are placed so that when the weight301 of the load controller 300 has fallen on the load target point, theload is imposed vertically by the load point 304 located at the tip ofthe weight 301 onto the load target point.

FIG. 11A shows the image obtained by the magnifying glass 402. Themicroscope of which the optical axis has a cross scale is combined witha CCD camera. The image data obtained by the CCD camera is transferredto the auto-controller 403.

The auto-controller 403 includes a microcomputer, an interface such asGPIB. A personal computer with an interface for image input from the CCDcamera is used.

The auto-controller 403 controls the location of the tip based on theimage data from the CCD camera. FIG. 11B shows the result ofbinarization of the image from the CCD camera.

The dotted line shows the lineament that would be shown if the work 1000were horizontal. In FIG. 11B, it is seen that the work 1000 is inclinedvertically. It should be adjusted to be horizontal by the goniostage ofthe stage 401.

In this embodiment it is possible to impose a constant load verticallyonto the tip of the plurality of the tips on the work 1000, resulting inprecise formation of apertures.

It is also possible to measure the inclination of all the tips and thestop person the work 1000 before forming the apertures, store theinclination in the auto-controller 403 before forming the aperturescontinuously.

In this embodiment, a combination of a CCD camera and an imageprocessing is used to measure the inclination that is caused by thecurve of the work 1000 and the variation of the film thickness. The samemeasurement can also be performed by a three-dimensional topologymeasurement device based on a known method of light interference.

In addition, the load controller 300 may control a direction of theloader to make the direction being perpendicular to the tip.

As described above, according to the apparatus for aperture forming inthis invention, it is possible to form an optical aperture in a stablemanner, because a constant load with high precision can be applied ontothe load target point repeatedly. Additionally, the cost of the wholeapparatus is low, which makes it possible to form an optical aperturewith low cost. Furthermore, the structure of the apparatus is so simplethat an automation of the aperture forming process is possible, and amass production becomes possible.

[Embodiment 6]

FIGS. 12A, 12B and 13 depict the apparatus for forming optical aperturesin embodiment 6. As shown in the drawing, the work 2001 comprises atransparent layer 5 formed on a substrate 4, a tip of conical orpyramidal shape land a ridge-shaped stopper 2 formed on the transparentlayer 5, and an opaque film 3 formed on the tip 1, the stopper 2 and thetransparent layer 5. A presser 7 is placed above the tip 1 and thestopper 2. The presser 7 can move only vertically. A cam 81 is placed togear with the groove made on the presser 7. The explanation on the shapeand the arrangement of the tip 1 and the stopper 2 is omitted, becauseit is the same as in embodiment 1. The side of the presser 7 that facesthe tip 1 is planar made of stainless steel, but this side may have aspherical shape, or have minute asperity as far as it is made of amaterial that is less deformable than the opaque film 3. The presser 7weighs several tens of grams in this embodiment, but in general itshould be determined according to the hardness of the opaque film 3, andthe dimension of the aperture.

The rotation of the cam 81 gradually lifts the presser 7 upward. Whenthe cam 81 reaches a predetermined angle, the cam 81 becomes free fromthe groove of the presser 7, and the presser 7 falls. The impact of thisfall causes a plastic deformation of the opaque film 3, and then anaperture is formed at the apex of the tip 1. As the cam 81 continues torotate, it comes again to gear with the groove of the presser 7, liftsthe presser 7, lets it fall again, and repeats these steps. A simplerotation such as described here leads the presser 7 to repeat falling.By using a mechanism that translates the substrate 4 horizontally inFIG. 13, it is possible to form aperture continuously with a simplestructure. Furthermore, the weight of the presser 7 or the altitude fromwhich the presser 7 falls determines the amount of pressing. It meansthat the aperture size can be designed easily, and apertures of the samesize can be formed in a stable manner. Additionally, the impact of thefall is given instantly so that aperture formation is possible withoutincreasing the weight of the presser 7 when the tip 1 is lower than thestopper 2.

Even when, as shown in FIG. 12B, the substrate 4 is not planar but iscontorted, it is possible to form the aperture of a predetermined sizeeasily by applying the pressure onto the substrate 4 vertically, becausethe presser 7 has the size just to cover the tip 1 and the portion ofthe stopper 2. Additionally, the pressed area by the presser 7 is small,which means that a small mass can cause a plastic deformation of theopaque film 3 and can form aperture infallibly.

In FIG. 13, a crank 82 is placed through the hole of the presser 7, andthe crank 82 is rotated by the motor 83. In this case, the presser 7repeats the vertical motion with respect to the substrate 4 owing to therotation of the crank 82. When the presser 7 comes to the lowest point,it presses the substrate 4, causing a plastic deformation of the opaquefilm 3, and forming the aperture. In this case, the presser deforms theopaque film 3 above two of the tips 1. In this way it is possible toform many apertures simultaneously. By using a mechanism that translatesthe substrate 4 horizontally in FIG. 13, it is possible to form manyapertures quickly. The mechanism for moving the presser 7 vertically canbe replaced by a conventional rack and pinion, hydraulic, air pressure,or screws. As described above, a simple structure is able to formapertures with high dimension precision, and reliability. It is madepossible to form many apertures quickly.

[Embodiment 7]

FIG. 14 depicts the apparatus for forming optical aperture in embodiment7. As shown in the drawing, the work 3001 comprises a transparent layer5 formed on a substrate 4, a tip of conical or pyramidal shape 1 and aridge-shaped stopper 2 formed on the transparent layer 5, and an opaquefilm 3 formed on the tip 1, the stopper 2 and the transparent layer 5. Arotating presser 7 is placed above the opaque film 3. The presser 7 isplaced such that as it applies pressure on the substrate 7, it rotatesto travel on the substrate 4. The explanation on the shape and thearrangement of the tip 1 and the stopper 2 is omitted, because it is thesame as in embodiment 1. The presser 7 is made of cast iron, and has theshape that resembles a gear. The presser 7 may have a shape of a cast,cylinder, or sphere. The presser 7 should be made of a material that isless deformable than the opaque film 3.

As the presser 7 applies pressure on the substrate 4, the surface of thepresser 7 causes a plastic deformation of the opaque film 3 above thetip 1 and the stopper 2, and an aperture is formed at the apex of thetip 1. Since the presser 7 rotates to travel on the substrate 4, it isable to form apertures continuously.

However, when the aperture is being formed by a plastic deformation ofthe opaque film 3, a portion of the opaque film 3, stopper 2, or the tip1 occasionally becomes an accretion 31 attached onto the surface of thepresser 7. If the presser 7 continues to rotate to travel, the accretion31 on the presser 7 attaches the tip 1 causing a failure of apertureformation. In this embodiment, the surface of the presser 7 stays cleanby a cleaner. In order to solve this problem, a discharge nozzle 91discharges either compressed air or fluid to remove the accretion 31. Asuction nozzle 92 takes in the accretion 31 with air to remove theaccretion 31 from the surface of the presser 7. Therefore, the surfaceof the presser 7 always stays clean, and one presser 7 is able to formmany apertures continuously and quickly.

There are other cleaners cleaning the surface of the presser. If theaccretion is dielectric, an electrically charged electrode approachesthe presser to pull the accretion by electrostatic force, removing theaccretion from the presser's surface.

Furthermore, as depicted in FIG. 15, a wiper 93 which is more deformablethan the presser 7 is pushed against the presser 7 so that a rotation ofthe presser 7 automatically leads the wiper 93 to wipe out the accretion31. In this apparatus, the surface of the presser 7 does not deformwhile removes the accretion, and it becomes possible to form aperturescontinuously in a stable manner.

Another apparatus can be presented as depicted in FIG. 16. A plasticprotective film 94 formed on the surface of the presser 7 is removedtogether with the accretion after an aperture is formed. In thisapparatus, the protective film 94 is always accretion-free when it ispushed for aperture formation, and it becomes possible to form aperturescontinuously in a stable manner.

Anther apparatus can be presented as depicted in FIG. 17. A film 95 isbound around the presser 7, and the film 95 is carried by the carrierrotor 84 in such a manner that the motion of the presser 7's surface andthat of the film 95 coincide. In this apparatus, a new clean surface ofthe film 95 is always supplied to the pressing surface for apertureformation, and it becomes possible to form apertures continuously in astable manner. Furthermore, the order of deformability should be, theopaque film 3, the film 95, the presser 7, the tip 1, and the stopper 2,from the least deformable to the most. By choosing the materials in thismanner, the tip 1 and the stopper 2 are the least deformable. Therefore,it is easy to form apertures of a uniform dimension. Furthermore, sincethe surface of the presser 7 is least deformable, it is easy to formapertures continuously.

[Embodiment 8]

FIGS. 18A, 18B and 19 depict the apparatus for forming optical aperturein embodiment 8. As shown in the drawing, the work 2001 comprises atransparent layer 5 formed on a substrate 4, a tip of conical orpyramidal shape 1 and a ridge-shaped stopper 2 formed on the transparentlayer 5, and an opaque film 3 formed on the tip 1, the stopper 2 and thetransparent layer 5. The explanation on the shape and the arrangement ofthe tip 1 and the stopper 2 is omitted, because it is the same as inembodiment 1.

The difference between this embodiment and the embodiment 1 is that thepresser 7 has a spherical shape facing the plate 6. The presser 7 ismade of stainless steel, and its tip radius of curvature is from severalhundred μm to several mm. The material of the presser 7 is notnecessarily stainless steel. Any material that has a higher rigidity andhardness than the plate 6 may function as the presser 7.

FIG. 18A depicts the state in which the presser 7 is not pressing theplate 6. FIG. 18B depicts the state in which the presser 7 is pressingthe plate 6 with the force F. When the presser 7 presses the plate 6,the force F inflects and elastically deforms the plate 6 toward the tip1, causing a plastic deformation of the opaque film 3, resulting in theformation of an aperture. As shown in this FIGS. 18A and 18B, if thepresser 7 has a spherical shape, the plate 6 is inflected toward the tip1. Therefore, even when the height difference ΔH between the tip 1 andthe stopper 2 is big, it is possible to form an aperture on the tip 1.Furthermore, locating the apex of the tip 1 is possible by observing theposition of the stopper 2 by either an optical microscope or imagerecognition system. Then the pressure area for the presser 7 can bedetermined. In this manner, the amount of the inflection of the plate 6toward the tip 1 is kept constant, and it becomes possible to formapertures with high dimension precision. When many apertures are formedcontinuously and when the height difference ΔH between the tip 1 and thestopper 2 varies considerably, a large amount of the inflection ensuresthe formation of an aperture. When the tip of the presser 7 is sharpenedmore, a small force F is able to cause a large inflection of the plate6, making it easy to form apertures.

FIG. 19 depicts an apparatus that the cylindrically shaped roller 27 ispressing the plate 6. The roller 27 is able to translate in thedirection indicated as D in the figure while pressing the plate 6. It isable to form apertures with high dimension precision, and furthermore,by leading the roller 27 to press and translate on a plurality of thework 2002, it is possible to form many apertures quickly.

[Embodiment 9]

FIGS. 20A and 20B depict the apparatus for forming optical A aperture inembodiment 9. As shown in the drawing, the work 3000 comprises atransparent layer 5 formed on a substrate 4, a tip of conical orpyramidal shape and a ridge-shaped stopper 2 formed on the transparentlayer 5, and an opaque film 3 formed on the tip 1, the stopper 2 and thetransparent layer 5. The explanation on the shape and the arrangement ofthe tip 1 and the stopper 2 is omitted, because it is the same as inembodiment 1.

The difference of this embodiment from the embodiment 1 is that thepresser 7 is made of a material softer than the plate 6. The presser 7is a silicone rubber several mm in thickness. A presser made of adifferent material may function as the presser 7 as far as the materialis softer than the plate 6.

FIG. 20B depicts the state in which the presser 7 is not pressing theplate 6. FIG. 20 b depicts the state in which the presser 7 is pressingthe plate 6 with the force F. When the presser 7 presses the plate 6with the force F, the opaque film 3 is plastically deformed, and anaperture is formed at the apex of the tip 1. When the plate 6 has arough surface facing the presser 7, the presser 7 deforms elasticallyaccording to the surface to pology of the plate 6, and a constantpressure is applied onto the plate 6. If the presser 7 had higherrigidity than the plate 6, there would be a variation of pressure on theplate 6, the plate 6 could not press the tip 1 vertically, giving riseto a variation of the aperture size and shape. By preparing a softpresser 7 as shown in FIGS. 20A and 20B, it is possible to formapertures of a uniform dimension and shape in a stable manner. Inaddition, as far as the surface of the presser 7 that faces the plate 6is made of a material softer than the plate 6, the object of thisembodiment is achieved.

[Embodiment 10]

FIG. 21 depicts the apparatus for forming optical aperture in embodiment10. As shown in the drawing, the work 4000 comprises a transparent layer5 formed on a substrate 4, a tip of conical or pyramidal shape 1 and aridge-shaped stopper 2 formed on the transparent layer 5, and an opaquefilm 3 formed on the tip 1, the stopper 2 and the transparent layer 5.The explanation on the shape and the arrangement of the tip 1 and thestopper 2 is omitted, because it is the same as in embodiment 1.

The difference of this embodiment from the embodiment 1 is that a grooveof inverted pyramid shape is formed on the plate 6, and the tip of thepresser 7 has a shape that can gear with the groove on the plate 6. Thepresser 7 is a cylinder made of stainless steel whose tip has a radiusof curvature between several hundred m and several mm. The plate 6 is arectangular quartz glass whose edge is several mm long. On the plate 6 agroove of inverted pyramid shape is formed. This particular shape andthe arrangement is one of many possible examples that a portion of thetip of the presser 7 can fit in the groove on the plate 6.

As depicted in FIG. 21, when the presser 7 presses the plate 6 with theforce F, the plate 6 inflects and elastically deforms toward the tip 1,plastically deforms the opaque film 3, resulting information of anaperture at the apex of the tip 1. The pressure area for the presser 7is determined by the position of the groove of the plate 6. Therefore,the amount of the inflection of the plate 6 can be controlled precisely.It is possible to form apertures of predetermined dimension and shapeprecisely and in a stable manner. Furthermore, the groove on the plate 6becomes a weaker structure locally, which leads the plate 6 to be moredeformable. It means that even when the tip 1 is lower than the stopper2 it is possible to form an aperture infallibly.

Furthermore, when either of the presser or the pressing body has aconcavo-convex shape, it is easy to define the load point for thepresser, thus making it possible to form apertures with high dimensionprecision in a stable manner.

[Embodiment 11]

FIG. 22 depicts the apparatus for forming optical aperture in embodiment11. A light guiding body 711 is deposited on the work 1001. On thesurface of the light guiding body 711 a sharpened tip 712 and thestopper 713 with similar height to the tip 712 are formed. An opaquefilm 714 is formed on the tip 712 and the stopper 713. The opaque film714 prevents the light from leaking from the tip 712. On one work 1001 aplurality of stoppers 713 and the tips 712 are formed. The number ofthose stoppers 713 and the tips 712 for each work 1001 is between 10 and1000. The shape and the arrangement of one group of the stoppers 713 andthe tips 712 are similar to that in FIGS. 4 and 5. The relative heightof the stoppers 713 and the tips 712 is similar to that in FIGS. 6 and7. The aperture that detects or generates near field is formed at theapex of those tips 712. The process of the aperture formation is similarto that in the embodiment 1 (described in FIGS. 1, 2 and 3.). Here it isexplained again referring to FIG. 22. The plate 715 covers the tips 712and the stoppers 713. The presser 716 presses the plate 715 towards thetips 712. A portion of the plate 715 inflects with respect to the edgeof the stoppers 713, and this portion contacts the opaque film 714 atthe apex of the tip 712. A plastic deformation of the opaque film 714forms the aperture. In this process of aperture formation, the work 1001is placed on a flat stage 717. The stage 717 has multiple holes 718 thatare connected to the tube 719 inside the stage 717. The end of the tube719 is connected to the pump 720 placed outside the stage 717. When thepump 720 is turned on and it vacuates the tube, the work 1001 is chuckedto the stage 717. With this chucking of the stage 717 by the vacuummechanism, the tips 712 and the stoppers 713 have almost the same heightin the entire surface of the work 1001.

Here the problem is presented for the state when there is no vacuumchucking. FIGS. 23–26 depict the state of the work 1002 when there is novacuum chucking. FIG. 23 depicts the work 1002 placed on the stage 721.The work 1002 comprises a substrate 722, a light guiding body 723, tips724, and stoppers 725. When different kinds of materials are depositedon a substrate, film tension is generated, and the entire substratecurves. For example, when the substrate 722 is made of silicon, and thelight guiding body 723 is made of silicon oxide, the work 1002 curvessignificantly as shown in FIG. 23 (in this case it points upwards). Ifthe work 1002 is placed on the stage 721 without vacuum chucking, someportions of the work 1002 contact the stage 721, but other portions donot contact the stage 721.

FIG. 24 depicts the state in which there is no vacuum chucking. Eventhough the tips (724 and 726) and the stoppers (725 and 727) have thesame height, because of the curve of the work 1002 their height from thestage 721 varies depending whether they are near the center of the work1002 or they are near the edge of the work 1002. Some stoppers 727contact the plate 728, but other stoppers 725 do not contact the plate728.

FIGS. 25 and 26 depict the state in which the presser 729 is pressingthe work 1002 with the plate 728 when the work 1002 is not vacuumchucked. At first, the plate 728 is in contact with the stoppers 727that are located near the center of the work 1002. The load from thepresser 729 causes the formation of an aperture at the apex of the tips726 that are located near the center of the work 1002. As the load iscontinuously applied, the work 1002 gradually becomes flat, and theplate 728 comes in contact with the stoppers 725 near the edge of thework 1002. The apertures near the edge of the work 102 are formedafterwards. As the work 1002 is becoming flat, the load which islocalized on the center deconcentrates, and some load starts to beapplied on the peripheral areas. However, the maximum load on the centerarea is larger than that on the peripheral area as shown in FIG. 26. Asa result, the size of the apertures near the center is larger than thatof the apertures on the peripheral area, causing an unwanted variationin the aperture size. The distribution of the aperture sizes is that itis large near the center, and becomes smaller in the peripheral area.This variation in the aperture size lowers the yield of the device, andcauses the increase of the production cost. FIG. 27 depicts the state inwhich the curved work 1003 is vacuum chucked onto the stage 730. Thework 1003 is made flat. The tips 731 and the stoppers 732 have the sameheight from the stage 730 in the entire surface of the work 1003. Thisis done by placing the work 1003 on the stage 730 before vacuumchucking. The work 1003 can be placed at any place on the stage 730.Another merit of the vacuum chucking is that it is easy to place andremove the work 1003. FIG. 28 depicts the state in which the plate 733is placed on the work 1003 that is vacuum chucked. The distance betweenthe stage 730 and the tips 731 is the same throughout the entire surfaceof the work 1003. The distance between the stage 730 and the stoppers732 is also the same throughout the entire surface of the work 1003. Asa result, the stoppers 732 on both the center area and the peripheralarea are in contact with the plate 733. FIG. 29 depicts the state inwhich load is applied by the presser 734 through the plate 733 onto thework 1003 which is vacuum chucked. As explained in FIG. 28, moststoppers 732 on the work 1003 are in contact with the plate 733. Theload applied by the presser 734 onto the stoppers 732 is constantthroughout the surface of the work 1003. Similarly, a constant load isapplied on the tips 731 without depending on the location. As a result,apertures of the same size are formed on the entire surface of the work1003. It is now possible to form apertures of the same size with highyield. It is also possible to form apertures of uniform size withoutvacuum chucking if a stage and a plate which have the same shape as thework are prepared. However, works with different curving cannot behandled in this way. When vacuum chucking is used, apertures of auniform size can be formed even when the work shave different degree ofcurving. Additionally, vacuum chucking is low cost in terms ofinstallation expense and maintenance because of its simple mechanismwhich has a tube through a hole in the stage connected to the pump.Alternative method for fixing the work on the stage may be a methodusing glue or wax, but removing the work from the stage or removing theglue from the work would be difficult. Another alternative method is touse screws, but there would be additional step to make holes on thework, and the cost would be high. The method of vacuum chucking hasother merits that removing the work is easy, the work is not damaged,and no cleaning is necessary.

In the explanation above, chucking is done by vacuum. Needless to say,there are other methods for chucking, for example, electrostatic forcebetween the electrode on the work and another electrode on the stage,or, magnetic force between the magnetic film on the work and anothermagnetic film on the stage.

Advantage of the Invention

By controlling the height of the tip 1, stopper 2, and the force F, itis easy to form aperture 8. An actuator with high resolution is notneeded. The height of the tip 1 and the stopper 2 is controlledprecisely. The yield of aperture formation is improved. The work 1000 inthe embodiment 1 can be fabricated using conventional photolithography.Multiple apertures can be formed on a work of a large area such as awafer. By keeping the force F to be constant, apertures of the same sizecan be formed on each of the work 1000. Since it is easy to change theforce F, it is possible to form apertures of different sizes for each ofmultiple works 1000.

Additionally, apertures are formed in a very short time, namely lessthan several tens of seconds for each aperture. This is because anaperture is formed by simply applying the force F. Besides, according tothe embodiment 1 of the invention, any fabricating atmosphere isacceptable. Therefore, fabrication in the atmosphere is possible andfabricating states can be observed by the optical microscopeimmediately. In addition, fabrication in the scanning electronmicroscope allows the fabricating states to be observed with higherresolutions than the optical microscope as well. Furthermore,fabrication in a liquid allows the liquid to serve as a damper and thusfabricating conditions with improved controllability can be obtained.

Additionally, multiple apertures having a uniform aperture diameter canbe produced at one time by applying the pushing force to the samplefabricated with a plurality of the works 1000 in the block. In the caseof fabrication in the block, the fabrication time per aperture becomesextremely as short as a few hundreds milliseconds or under, depending onthe number of the works 1000 per wafer.

Additionally, since the amount of the deformation of the opaque film 3is determined by the weight of the presser 7, the height from which theweight falls, or the force of the pressing, it is possible to formapertures of the same size easily in a stable manner. When the presser 7repeats vertical motion, a simple structure can form apertures with highdimension precision, in a short time infallibly. Mass production of theapertures is also possible. The production cost becomes very low. Whenthe presser 7 falls to cause an impact to form an aperture, the impactis applied instantaneously. Therefore, even when the tip 1 is lower thanthe stopper 2, an aperture can be formed without increasing the weightof the presser 7. When the presser 7 has a size that covers the tip 1and a portion of the stopper 2, load is applied vertically on thesubstrate 4 automatically even when the substrate 4 is distorted. It iseasy to form apertures of the same size on the tip 1. Since the pressurearea for the presser 7 is small, a small mass can cause plasticdeformation of the opaque film 3, and apertures can be formedinfallibly.

Additionally, when the cleaner removes the accretion from the surface ofthe presser 7, one presser 7 can continuously be used to form aperturesin a stable manner, resulting in lowering the production cost. When thesurface of the presser 7 is protected by a protective film that isremoved together with the accretion after aperture formation, and whenthe opaque film 3, the protective film, the presser 7, tip 1, and thestopper 2 are in this order from the least deformable to the mostdeformable, it is easy to form apertures of a uniform size continuously.

Additionally, when the tip of the presser 7 has a spherically convexshape facing the plate 6, it is easy to increase the amount ofinflection, and an aperture can be formed on the tip 1 even when theheight of the tip 1 and that of the stopper 2 differ much. Bycontrolling the pressure point of the presser 7 it is possible to keepthe amount of the deformation of the plate 6 constant, thus to formapertures with high dimension precision. When multiple apertures areformed continuously but the height difference ΔH between the tip 1 andthe stopper 2 has a large variation, apertures can be formed infalliblybecause the amount of inflection is kept large. When the tip of thepresser 7 is sharpened even more, a small force F can cause a largeinflection of the plate 6, thus making it easy to form apertures. When apresser roller 27 of a cylindrical shape presses the plate 6, the roller27 can press the plate 6 with the force F while traveling horizontally,thus it is possible to form many apertures quickly with high dimensionprecision in fallibly.

Additionally, when the presser 7 is softer than the plate 6, a constantforce can be applied even when the surface of the plate 6 is not flat,thus making it possible to form apertures of the same size and shape ina stable manner.

Additionally, when the plate 6 has a groove of inverted pyramidal shape,and the presser 7 has a tip which gears with the groove, it is easy todetermine the pressure point, thus making it possible to form apertureswith high dimension precision. Furthermore, the portion of the plate 6where the groove is formed is more deformable than the other portions ofthe plate 6. Even when the tip 1 is lower than the stopper 2, aperturecan be formed infallibly.

Additionally, by fixing the work by vacuum chucking, it is possible toform apertures of the same size and shape on the work even when the workcurves. When each work has different degrees of curve, same sizedapertures can be formed. Therefore, the yield of the aperture formationimproves, thus lowering the cost. The apparatus and its maintenance islow cost. Other advantages are, it is easy to uninstall the vacuumchucking mechanism, the work is not damaged, or no cleaning is needed.

1. An apparatus for forming an optical aperture in an object having atip with a pointed end and a plurality of stoppers disposed adjacent thetip, the apparatus comprising; a pressing body for pressing the pointedend of the tip and at least a part of each of the stoppers of the objectto form an optical aperture at the pointed end of the tip; a loader forapplying a loading force on the pressing body to press the pointed endof the tip and the part of each of the stoppers; a magnifying glass formeasuring a curvature of the object; and a load controller forcontrolling a direction of the loading force applied by the loader onthe pressing body in accordance with the curvature of the objectmeasured by the magnifying glass so that the direction of the appliedloading force is generally perpendicular to the pointed end of the tip.2. In combination: an object having a tip with a pointed end and aplurality of stoppers disposed adjacent the tip; a pressing body forpressing the pointed end of the tip and at least a part of each of thestoppers of the object to form an optical aperture at the pointed end ofthe tip; a loader for applying a loading force on the pressing body topress the pointed end of the tip and the part of each of the stoppers;and a load controller for controlling the loading force applied by theloader on the pressing body.
 3. An apparatus according to claim 2;wherein the load controller comprises a rotational gear connected to theloader for undergoing rotation to drive the loader into pressure contactwith the loader to apply a loading force to the pressing body.
 4. Anapparatus according to claim 3; wherein the load controller furthercomprises a motor for rotationally driving the rotational gear; andfurther comprising control means for controlling a rotational speed ofthe motor to control a magnitude of the loading force applied by theloader to the pressing body.
 5. An apparatus according to claim 3;wherein the loader has a tip portion for contacting a load target pointof the pressing body.
 6. An apparatus according to claim 5; wherein thetip portion of the loader is generally spherical-shaped.
 7. An apparatusaccording to claim 2; wherein the loader comprises a biasing memberhaving a tip; and wherein the load controller comprises a rotationalgear for undergoing rotation to bias the biasing member to bring the tipof the biasing member into pressure contact with the pressing body toapply the loading force to a load target point of the pressing body. 8.An apparatus according to claim 7; wherein the load controller has amotor for rotationally driving the rotational gear; and furthercomprising control means for controlling a rotational speed of the motorto control a magnitude of the loading force applied by the tip of thebiasing member to the load target point of the pressing body.
 9. Anapparatus according to claim 7; wherein the tip of the biasing member isgenerally spherical-shaped.
 10. An apparatus according to claim 2;wherein the loader comprises a magnetized core having a tip; and whereinthe load controller comprises a coil wound around the magnetized corefor receiving an electric current to move the magnetized core to bringthe tip thereof into pressure contact with the pressing body to applythe loading force to a load target point of the pressing body.
 11. Anapparatus according to claim 10; wherein the tip of the magnetized coreis generally spherical-shaped.
 12. An apparatus according to claim 10;further comprising control means for controlling the amount and durationtime of the electric current received by the coil to control a magnitudeof the loading force applied by the tip of the magnetized core to theload target point of the pressing body.
 13. An apparatus according toclaim 2; further comprising an opaque film disposed on the tip and thestoppers so that the pressing body presses the pointed end of the tip,at least a part of each of the stoppers, and at least a part of theopaque film to form the optical aperture at the pointed end of the tip.14. In combination: an object having a tip with a pointed end and aplurality of stoppers disposed adjacent the tip; a pressing body forapplying a loading force to press the pointed end of the tip and atleast a part of each of the stoppers of the object to form an opticalaperture at the pointed end of the tip; and a load controller forcontrolling the loading force applied by the pressing body.
 15. Anapparatus according to claim 14; wherein the pressing body has a groove;and wherein the load controller comprises a rotational cam having a gearportion for engaging the groove of the pressing body so that duringrotation of the rotational cam, the gear portion engages the groove ofthe pressing body and displaces the pressing body against the force ofgravity until the gear portion is disengaged from the groove when therotational cam reaches a preselected rotational angle at which point thepressing body falls under the force of gravity to apply the loadingforce and press the pointed end of the tip and at least a part of eachof the stoppers to form the optical aperture at the pointed end of thetip.
 16. An apparatus according to claim 14; wherein the pressing bodyhas a hole; and wherein the load controller comprises a rotational crankhaving a driving portion extending through the hole of the pressing bodyso that during rotation of the rotational crank, the driving portiondrives the pressing body in a first direction until the rotational crankis rotated through a preselected rotational angle at which point thedriving portion drives the pressing body in a second direction oppositeto the first direction to apply the loading force and press the pointedend of the tip and at least a part of each of the stoppers to form theoptical aperture at the pointed end of the tip.
 17. An apparatusaccording to claim 14; further comprising an opaque film disposed on thetip and the stoppers of the object so that the pressing body presses thepointed end of the tip, at least a part of each of the stoppers, and atleast a part of the opaque film to form the optical aperture at thepointed end of the tip.
 18. An apparatus according to claim 14; furthercomprising a plate disposed over at least the tip and the stoppers ofthe object; and wherein the pressing body has a pressing portion forapplying the loading force to the plate to press the pointed end of thetip and at least a part of each of the stoppers to form the opticalaperture at the pointed end of the tip.
 19. An apparatus according toclaim 18; further comprising an opaque film disposed on the tip and thestoppers of the object so that the plate presses the pointed end of thetip, at least a part of each of the stoppers, and at least a part of theopaque film to form the optical aperture at the pointed end of the tip.20. An apparatus according to claim 18; wherein the pressing portion ofthe pressing body is generally spherical-shaped.
 21. An apparatusaccording to claim 20; further comprising an opaque film disposed on thetip and the stoppers of the object so that the plate presses the pointedend of the tip, at least a part of each of the stoppers, and at least apart of the opaque film to form the optical aperture at the pointed endof the tip.
 22. An apparatus according to claim 18; wherein the pressingbody comprises a generally cylindrical-shaped roller.
 23. An apparatusaccording to claim 22; further comprising an opaque film disposed on thetip and the stoppers of the object so that the plate presses the pointedend of the tip, at least a part of each of the stoppers, and at least apart of the opaque film to form the optical aperture at the pointed endof the tip.
 24. An apparatus according to claim 18; wherein the pressingbody is made of a material softer than that of the plate.
 25. Anapparatus according to claim 24; further comprising an opaque filmdisposed on the tip and the stoppers of the object so that the platepresses the pointed end of the tip, at least a part of each of thestoppers, and at least a part of the opaque film to form the opticalaperture at the pointed end of the tip.